#include <iostream>

using namespace std;

int com(int m,int n);

int main ( )
{
    int m,n,c;
    cout<<"please enter the number of element,and the size of group"<<endl;
    cin>>m>>n;

    c=com(m,n);

    cout<<c<<endl;

    cin>>c;
    return 0;
}

int com(int m, int n)
{
    int i,j,c;

    for(i=1;i<n;i++)
        {
            n=n*(n-i);
        }

    for(j=1;j<m;j++)
        {
            m=m*(m-j);
        }

    c=n/m;

    return c;
}






